TOF PID results in Au Au and d Au

1
TOF PID results inAuAu and dAu
Frank Geurts for the TOF group

• Apparatus Data sets
• AuAu
• calibration
• PID results
• particle ratios RFF/FF problem
• simulation embedding status
• dAu
• calibration
• PID results
• spectra hadron, B/Nch, single-e
• Summary Outlook

2
TOF pVPD TOFx, xp,r

• AuAu
• detectors
• start pVPD (2.and.2)
• stop TOFp
• this data set central (830k)
• other data sets minbias, 22GeV
• dAu
• detectors
• start pVPD (1.and.1)
• stop TOFr TOFp
• this data set
• dAuTOF (2M)
• dAuMinBias, dAuCombined (6.5M)

3
AuAu start time calibration
Bill Llope

• all 6 tubes fired for every event
• slewing effect
• iterative techniques based on difference of
  averages lt2gt-lt4gt
• lt2gtltEiWigt, i1..3
• lt4gt?ltEjWjgt, j?i
• raw start time resolution 70ps
• after corrections 24ps
• done

4
AuAu TOFp track matching

• TOFp 41 slats, ?f6, ??1
• occupancy in central evts 40
• 133 tracks/tray/evt for central data
• effective inside tray acceptance 51
• 41Aslat/Atray 60
• 6 dead slats 85
• high multiplicity
• singly-tracked slats
• single-slat tracks
• primary track match 2.5 per event (8)

ADC TDC
AuAu central
AuAu minbias
22GeV
dAu
pp
5
AuAu stop time calibration

• single-ended slats
• light propagation 65ps/cm
• slat length 20cm
• hit position correction
• pulse-height dependence, slewing
• light attenuation (position dependent!)
• momentum dependent (Bethe-Bloch)
• track length inside slat
• optimize iteratively in (1/ß)exp (1/ß) p
• no momentum cuts used to select calibration ps
• done.

1/ß
Bill Llope
zhit
zhit
adc
adc
adc
zloc
1/ß
zloc
adc
zloc
adc
Bill Llope

• total (startstop) time resolution in central
  AuAu
• averaged over all slats 87ps
• averaged over the best 25 slats 79ps

6
AuAu PID
Bill Llope

• TOFp PID¹
• p/K separation up to 1.9GeV/c
• (pK)/p separation up to 3.1GeV/c
• more details
• TOFp NIM paper
• talk by Bill Llope in spectra parallel session on
  Sat.
• ¹) PID ranges based on (11) s

7
AuAu particle ratios problem

• B-field problem in h-/h
• h-/h ratio per slat
• slight F-dependence

FF
RFF
p-/p
pbar/p
K-/K
8
AuAu particle ratios, RFF/FF

• significant enhancement in m-/m spectra below
  pTlt0.5GeV/c for FullField compared to Reversed
  FullField.
• no B-field dependency in matching code
• bias introduced in mDST?
• compare same run sample for mDST and event.root
• no difference in final m-/m spectra
• indication of field dependency in the track input
  distribution
• select on very good tracks
• fitpointsgt35
• even stronger effect
• vary DCA cut
• stronger effect for smaller DCA cut
• weaker effect for larger DCA cuts
• maximize DCA cut
• effectively removing the primary track
  requirement
• RFF/FF effect seems to have disappeared

• matched TOFp tracks
• 30ltTDClt1200
• fitpointsgt20, ?2lt2.

FF
RFF
no DCA cut
FF
RFF
9
AuAu RFF/FF (contd)

• dead pads or RDOs?
• west TPC has dead pads close to TOFp position
• no dead pads on East TPC side
• no obvious differences from Zvtxlt-25cm vs.
  Zvtxgt25cm
• geometrical effect?
• small f-acceptance detector!
• low pT primary tracks large curvature
• pT lt 1.4GeV/c tracks can pass through sect.19 and
  18 (depending on chargeB)
• pT lt 0.49GeV/c all primary tracks will pass
  through either sects 18,19,20

Olga Barannikova
10
AuAu RFF/FF (contd)

• sector boundary crossing?
• RFF
• neg. tracks pTlt0.7GeV/c (lt0.22GeV/c)
• pos. tracks pTlt0.37GeV/c
• FF
• neg. tracks pTlt0.37GeV/c
• pos. tracks pTlt0.7GeV/c (lt0.22GeV/c)
• hint from max gap distributions
• increasing max gap size as a function of pT
• consistent with large path in between sectors for
  smaller curvatures, i.e. larger pT
• energy loss for low momentum tracks
• effective pT thresholds different then those
  based on a pure helix model
• TOFp tray is asymmetrically positioned in
  sect.19
• closer to sect.18 then 20
• therefore different effect w.r.t. field setting
• more simulations required
• corrections from embedding

11
TOFp simulation embedding

• slat signal simulations
• ADC distributions match
• introduce individual slat gain factors
• embedding
• match efficiency
• ADC thresholds
• RFF/FF effect

• based on TPC track embedding
• not enough statistics
• massive TOF embedding after analysis meeting

12
dAu TOFp TOFr

• TOFr tray prototype for Full Barrel TOF
• 72 digitized out of 168 available channels
• ?f6, ??0.4
• very successful and stable operation
• large data sets, dedicated TOFr trigger
• dAuMinbias dAuCombined 6.6M pVPD physics
  events (25M STAR evts)
• 1.6M TOFp counts (0.24 per pVPD physics evt)
• 0.7M TOFr counts (0.10 per pVPD physics evt)
• 45k hits/TOFp-slat, 12k hits/TOFr-cell
• dAuTOF 2.0M pVPD physics events (2.5M STAR
  events)
• 630k TOFp counts (0.32 per pVPD phys evt)
• 2.4M TOFr counts (1.22 per pVPD phys evt)
• 15k-25k TOFp hits/slat 25k-45k TOFr hits/cell
• TOFr analysis based on dAuTOF

13
dAu start time calibration

• pVPD coincidence changed to 1.AND.1
• east pVPD sees Au fragments
• 2.4 hits per event
• west pVPD sees d fragments
• 1.3 hits per event
• time resolution better on the east pVPD, worse on
  west
• single-detector equivalent time resolutions
• east 110ps
• west 170ps
• see Bills talk in spectra PWG session

based 5M pVPD evts, days 24-55
fraction of pVPD phys evts for various east/west
configurations
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dAu TOFr calibration
Lijuan Ruan

• low multiplicity
• straightforward matching procedure
• small hit position correction
• perform slewing and hit position correction in
  subsequent steps
• non-linear TDC range
• in-situ calibration
• moved the TOFr TDC common-start for pp run
• overall TOFr resolution 120ps

capable of p/(pK) separation up to 3GeV/C
15
dAu TOFp calibration

• just off the press !!!
• pVPD for full pVPD data set
• pVPD E3 W1 (40)
• preliminary separations 1.5GeV/c and 2.5GeV/c

16
dAu hadron spectra
Lijuan Ruan

• based on TOFr data with dAuTOF trigger
• corrected for
• absorption
• matching efficiency

17
dAu baryon/Nch ratio
Lijuan Ruan
Lijuan Ruan

• no difference between multiplicity bins
• small mass dependence of Cronin effect for this
  energy
• large difference from AuAu!!
• prominent final state interactions in AuAu
• pp data for R(dAU)

• comparison to pbarp _at_1.8TeV
• similar
• comparison to p/N at lower energies
• comparable
• clear A dependence in pA collisions
• More details see Lijuans talk today

18
dAu single-electron spectra
Xin Dong

• complicated electron ID from TPC dE/dx
• cross-over regions
• use TOF PID cut to separate e-band
• 1-1/ß lt0.03

Xin Dong
19
dAu open charm production
Xin Dong

• single electrons pTgt1GeV/c from heavy-quark
  production
• large background
• ? conversion
• pº, ? Dalitz decays
• K decays
• ?, ?, f
• MC study on ?-conv. and pº Dalitz-decay BG
• increasing excess in data/BG ratio at high pT

Xin Dong

• remaining BG from ? (Dalitz) and ?, ?, f decays
• contribution from charmed decay

20
dAu open charm (contd)
Xin Dong

• very preliminary acceptance and efficiency
  correction
• background-subtracted (ee-)/2 spectrum
• more details see Xins talk on Saturday

PHENIX, PRL88 (2002) 192303
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Summary Outlook

• AuAu analysis
• calibration done
• ready for spectra, however...
• RFF/FF problem identified
• dAu analysis
• TOFr worked and is producing physics!!!
• pVPD and TOFr calibrated for dAuTOF trigger
• exciting new results and analyses
• (ppbar)/Nch up to 3GeV/c (Lijuan)
• single-e spectra (Xin)

• AuAu
• embedding
• dAu
• final calibration of pVPD and TOFp,r for
  dAuMinbias and dAuCombined trigger
• TOFx embedding
• pp
• calibration of pVPD and TOFp,r
• R_dAu !!
• papers ...

22
TOF talks _at_ Analysis Meeting

• Lijuan Ruan
• PID spectra from TOFr in dAu
• today 17h20
• Xin Dong
• Single Electron Spectra from TOFr capability,
  background study and open charm
• Sat. 9h00, Spectra PWG
• Bill Llope
• TOF analysis/calibration
• Sat. 14h10, Spectra PWG

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(11)s separation and s(t)
d/(pKp)
p GeV/c
m GeV/c2
p/(pK)
?1
?0
p/K
s(t) ps
p GeV/c
25
Cronin effect

• s(pA) Aa s(pp)
• large effect for p compared to p and K

• p/p ratio in pW changes for different energies
• different energy dependence of ap and ap

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(e-e)/2 PHENIX vs. STAR
PRL88 (2002) 192303